[mcstas-users] Problem about single-crystal virtual experiment in McStas

Thu Apr 3 15:15:14 CEST 2025

Hi Erxi,
(Hope it is OK that I cc mcstas-users at mcstas.org<mailto:mcstas-users at mcstas.org> since your observation/issue may be relevant to other McStas users also. :-) )

Which version of McStas are you running? As I remember a minor fix was made (relating only to the printed orientation output I think) somewhere between  ~ McStas 3.4 and now.

With the attached instrument (adapted from templateLaue.instr) and the latest McStas (i.e. 3.5.24 or 25) seem to get reasonable output with:

Your wanted orientation:
mcrun templateLaue.instr ay=0 -d all_pars_default --autoplot
i.e.
Direct space lattice orientation:
  a = [-7.1422 0 7.1422]
  b = [7.1422 0 7.1422]
  c = [0 10.1006 0]
Reciprocal space lattice orientation:
  a* = [-0.439863 0 0.439863]
  b* = [0.439863 -0 0.439863]
  c* = [0 0.622061 -0]

The default orientation from the .lau file:
mcrun templateLaue.instr ax=0 ay=0 az=0 bx=0 by=0 bz=0 cx=0 cy=0 cz=0 -d all_pars_0 --autoplot
i.e.:
Direct space lattice orientation:
  a = [0 10.1006 6.18483e-16]
  b = [0 0 10.1006]
  c = [10.1006 6.18483e-16 6.18483e-16]
Reciprocal space lattice orientation:
  a* = [-3.80902e-17 0.622061 0]
  b* = [-3.80902e-17 -3.80902e-17 0.622061]
  c* = [0.622061 0 0]

I attach the instrumentfile used, plots and datasets.

Best,
Peter

[cid:f11ed2c4-7392-4543-9dbe-ce8d6822b25d at EURP192.PROD.OUTLOOK.COM]
[cid:eb787252-4a5e-45a9-85c2-f6d395b8604f at EURP192.PROD.OUTLOOK.COM]

On 3 Apr 2025, at 11.02, Erxi Feng <fengex at ihep.ac.cn> wrote:

Dear Peter

I tried to use Single_crystal component in Mcstas to simulate the time-of-flight single-crystal diffraction with incident wavelength 0.5 to 6.5 AA. I used cif2hkl to generate the lau file of Ho2Ti2O7. However, I cannot rotate the lattice by setting the ax, ay, az, bx, by, bz, cx, cy, cz. Parameter. No matter what numbers I input to Single-crystal component, Mcstas always using the orientation with a-axis in y, b in c, and c in x. Is there something wrong or bugs? Could you please help me to solve the problem? See detail in the attachment.

Best
Erxi Feng
[cid:0a3d39e0-c1cc-423f-97be-a651cffe6cb2 at EURP192.PROD.OUTLOOK.COM]

[cid:9876a189-c491-41ef-b326-bcb21cb5c41b at EURP192.PROD.OUTLOOK.COM]

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
冯尔玺
中科院高能物理研究所东莞研究部
散裂中子源科学中心
联系电话：0769-8893 1537（分机：1537）
邮箱：fengex at ihep.ac.cn<mailto:fengex at ihep.ac.cn>
地址：广东省东莞市大朗镇中子源路1号 中国散裂中子源园区A1-628

邮编：523803

Erxi Feng
China Spallation Neutron Source (CSNS)
No.1 Zhongziyuan Road, Dalang,
Dongguan, 523803
Guangdong Province, China
E-mail: fengex at ihep.ac.cn<mailto:fengex at ihep.ac.cn>
Tel: +(86) 0769-89156971
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Peter Kjær Willendrup
Forskningsingeniør, Specialkonsulent

DTU Physics

[cid:7cce87e4-7b2a-4f35-9d56-6d8825b241ac at EURP192.PROD.OUTLOOK.COM]

Technical University of Denmark

[cid:a120cfd5-0aab-42de-be38-172b9fcfb70b at EURP192.PROD.OUTLOOK.COM]

Department of Physics
Fysikvej
Building 307
DK-2800 Kongens Lyngby

Main office at
ESS DMSC
Building 305
DK-2800 Kongens Lyngby

Direct +45 2125 4612
Mobil +45 2125 4612
Fax +45 4593 2399
pkwi at fysik.dtu.dk

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